直接键连原子间的NMR偶合常数的自然杂化轨道研究V.13C-13C和13C-31P核自旋偶合常数1JCC和1JCP

在前文工作的基础上,结合MNDO/EHMO分子轨道方法和自然杂化轨道方法,具体计算了C-C键和C-P键的核自旋偶合常数.计算结果表明,¹J_CC和¹J_CP主要由成键原子的轨道杂化作用和键极性这两种结构因素所决定.为从简单价键理论角度解释和计算¹J_CC和¹J_CP值提供了简便直观的方法.

THE STUDY OF THE NUCLEAR SPIN-SPIN COUPLING CONSTANTS BETWEEN DIRECTLY BONDED ATOMS BY NATURAL HYBRID ORBITALS V.13C-13C and 13C-31P Nuclear Spin-Spin Coupling Constants 1JCC and 1JCP

The novel generalized correlation of the nuclear spin-spin coupling constants with the atomic hybrids and net charges is employed to give new concrete relationships for calculating the directly bonded carbon-carbon and carbon-phosphorus coupling constants by use of the natural hybrid orbital procedure together with the MNDO/EHMO calculation.The calculated values are well in agreement with the experimental data, which suports the idea that the hybridization and bond polarity, and the Fermi contact term are dominant factors in determining carbon-carbon and carbon-phosphorus spin-spin coupling constants across one bond.Thus one is able to interpret and calculate the ¹J_CC and ¹J_CP values based on the simple valence bond theory.